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A/C system testing

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White70JavelinSST View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Topic: A/C system testing
    Posted: Sep/30/2014 at 5:30pm
I finally got the system in the WhiteJavelin completed.
It has all been converted to O ring fittings, I found a NOS condenser for a 74 javelin, it worked, made O ring fitting ends out of brass for the evap coil, bought a new O ring expansion valve, dryer, everything.

So I borrowed a fill gauge setup and a vacuum pump. The system will pull a vacuum very quickly and hold it for a least an hour, however over night the vacuum is gone. I disconnected the gauge setup for the over night test and used a phillips screwdriver to push in the valve in the morning, no air being sucked in.

I believe I have a leak.

So, I need to fill the system with nitrogen or argon or something.

or do I even have a leak?? Should the system be capable of holding  a vacuum for that long with just the standard 134A fill valves? I did put the caps back on.

Is there an A/C guru out there to give me some pointers?

I could use help figuring out the best approach to testing this system with pressure to find the leak.



Thanks all,

Armand
70 Javelin SST, second owner, purchased 1972
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dltowers Quote  Post ReplyReply Direct Link To This Post Posted: Sep/30/2014 at 5:41pm
Hello Armand,
I had a similiar situation with my wife's 1974 Javelin.
If you are still using the York Compressor it may be the issue.
Everything on the system of the wife's Javelin was new/rebuilt, except the old York Compressor.
The cooling system would charge up and hold a charge maybe 1/2 day then be down.
The A/C Shop done a pressure check and found that the front seal on the York Compressor was leaking oil. 


Edited by dltowers - Oct/03/2014 at 9:39am
Original Owner, 1974 Javelin:
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G4 Plum exterior with 421Q Black Uganda Interior. Purchased on July 16, 1974 from Hooker AMC, Sherman, TX for $4500.20
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6768rogues Quote  Post ReplyReply Direct Link To This Post Posted: Sep/30/2014 at 6:22pm
If it will not hold vacuum, it has a leak. I got busy when I did the AC in my Rogue and left the vacuum in for two weeks and the gauge did not budge.
If you cannot find the leak, I think it can be dye tested.
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White70JavelinSST View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Sep/30/2014 at 7:05pm
I shoul dhave mentioned that the compressor has been changed to a Sanden style.

I will need to charge the system to install the dye, then the refrigerant leaks out.

I'm trying to get away from that.

Any ideas?

Armand



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Post Options Post Options   Thanks (0) Thanks(0)   Quote nitrousamcrambler Quote  Post ReplyReply Direct Link To This Post Posted: Sep/30/2014 at 7:57pm
I also run into this problem with a worn and new a/c clutch seal, So under vaccum  It will cause the ac compressor seal to suck inwords causing it not to hold a vac, But under pressure it will push the seal out words and hold pressure, Best thing to do is add Dye And easter oil and run the system. put my bet its just the seal that is being suck in words and will be fine once 134a will be added. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2014 at 5:53am
A/C troubleshooting is very fun stuff!!!  If the gauge moves from 30 inches of vacuum, you have a leak, if it is overnight to zero, you have a sizeable leak in the A/C world.  You need a accurate "sniffer" for A/C leak, some very high end ones can find leaks so small it is incredible.  I will put a disclaimer in here, it costs a lot of money to be in compliance with Federal Rules on A/C systems.....Gauge set ups with check valves, reclaimers, license to do A/C work, etc.....I bit the bullet many years ago and this is why it is so expensive to have the work done...   I troubleshooting you really need a reclaimer to be "legal", you do not dump system to atmoshpere and that is what it requires if you don't have a reclaimer.   Okay, off the soapbox.  (Sorry)...When I troubleshoot, I will put in a very small charge of Freon, then sniff everywhere for leaks until I find the source.  Once found, perform repairs...not going into specifics here.  Another method is to put dye in the system. Did you put oil in the system, it is necessay fo the system to work properly.  For every "new" component (compressor..if not factory precharged with oil, condenser, evap, etc{not expansion valve}), you are to add one ounce of oil, on a fresh system everything new or flushed clean, I never put more then 3 ounces in whole system....the point here is I always use oil that has dye in it to begin with and saves a step if there is a leak now or in future. To check the dye you will need a black light and the dark........the dye method is very good also, but look at everything.  Last two leaks I helped trouble shoot were both leaking hoses.  One was an old hose, with pin hole and another was new hole that wasn't crimped well.  Let me know if I can help anymore, hope this helps.
Ross K. Peterson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2014 at 8:25am
Thanks for the replies guys.

To add more info about the system.

Everything is new except the evap coil. The coil has brass O-ring adaptors silver soldered in place of the flare adaptors. Everything is either welded aluminum tubing or stainless steel barrier hose. Everything has been converted to O-ring fittings. The compressor is a new Chinese knock off of a Sanden. I put the appropriate amount of oil directly into the oil fill port on the compressor. 401 MatCoupe, thanks for reminding me, the oil has green dye in it!.

So far no one has said that it's smart to test with nitrogen or argon. Instead I'm hearing I should introduce R134A, dye and test for leaks with a sniffer or the black light method. That's great but not very do-able at home, without releasing R134A into the atmosphere. I'm beginning to think I need to take the car to a A/C specialist so they can recover the R134A for me after testing it that way.

Question for 401MatCoupe, Will a hydrocarbon sniffer work? I have many friends in the natural gas business that utilize hydro carbon sniffers. R134A is Tetrafluoroethane, which I think is a hydrocarbon molecule. I don't know of any local A/C guys with a sniffer. Most use the black light trick.

Still, though, I think there must be a place that has a test hose adaptor available to introduce either nitrogen or Argon into the system.

Thanks again.

Armand

Edited by White70JavelinSST - Oct/01/2014 at 8:29am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2014 at 8:54am
Here's a photo of an adaptor available on Ebay. I think I found a method to introduce nitrogen into an auto A/c system

With this adaptor, using flare to IPS fittings and a pressure gauge with a 500 psi max reading or more, I can make a test gauge setup with a shut off valve, connect that to a regulator on a bottle of dry nitrogen and pressurize the A/C system with nitrogen. I should be able to check for leaks with soapy water if I can't hear the leak.


Low and high side adaptors are available, low cost too, like $20 or less for both & free shipping

Armand
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2014 at 11:52am
I don't know if a "hydrocarbon" sniffer will work....I have no idea...sorry.  I see no issue of introducuing a "Dry Inert gas"....I would never put compressed shop air in though, it will have way to much moisture in it.  We use compressed Helium in testing of aircraft fuel lines becasue of its small molecole size...but the sizeable leak you have described should show wiht a soapy water solution misted over the components and fittings.  Make sure you limit the test pressure to no more then 300 psi, which is about how high I have seen R134A reach on very hot summer day....and that may be high, however the system operating pressure at 100 degrees Outside Air Temp is about 225 psi max (off the top of my head), this would mean the a proof pressure would be 1.5 times 225psi or 337psi...I believe 300 is safe pressure to ensure the system is tight and will last a very long time.  Just remember R134A always has a higher (relative to R12) operating pressure.
Ross K. Peterson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote greasygt III Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2014 at 3:15pm
    DON'T go higher than 110 psi. That is an average static pressure for the A/C
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